If you have a fever or any other symptoms of COVID-19 or if you have received instructions from Public Health to self-isolate because of COVID-19, you must postpone getting vaccinated.
The following COVID-19 messenger RNA vaccines are currently available in Québec:
- The Pfizer/BioNTech vaccine, approved for people 12 years of age and older;
- The Moderna vaccine, approved for people 18 years of age and older.
Where to get vaccinated
Go to the COVID-19 vaccination campaign page to find out the procedure for getting vaccinated.
How the vaccine works and ingredients
Vaccination prepares your body to defend itself against any microbes it may encounter.
The virus that causes COVID-19 is composed of a strand of genetic material, RNA (ribonucleic acid), surrounded by an envelope. On the surface of the virus, there are proteins, including the S protein (spike protein) which gives it its crown shape, hence its name coronavirus. The S protein allows the virus to infect cells in the human body.
COVID-19 messenger RNA vaccines block the S protein, preventing the virus from entering and infecting human cells.
The Pfizer/BioNTech vaccine contains:
- messenger RNA;
- lipids (ALC-0315 = ((4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate), ALC-0159 = 2-[(polyethylene glycol)-2000]-N,N-ditetradecylacetamide, 1,2-Distearoyl-sn-glycero-3-phosphocholine and cholesterol);
- salts (potassium chloride, dibasic sodium phosphate dihydrate, sodium chloride, monobasic potassium phosphate
- sugar (sucrose).
The Moderna vaccine contains:
- messenger RNA;
- lipids (1,2-distearoyl-sn-glycero-3-phosphocholine, SM-102, polyethyleneglycol-2000 DMG (1,2-dimyristoyl-rac-glycerol, methoxy-polyethylene glycol) and cholesterol);
- solvents (tromethamine, tromethamine hydrochloride, acetic acid)
- sugar (sucrose).
Number of doses
Two doses of COVID-19 messenger RNA vaccine are required. Both doses are administered intramuscularly. The 2nd dose is needed for long-term protection.
People who received a viral vector-based vaccine (AstraZeneca or Covishield) for the 1st dose could receive a messenger RNA vaccine for their 2nd dose. Go to the Second dose of COVID-19 vaccine page for more information.
People who have had COVID-19 before receiving the vaccine only need 1 dose. For more information, see Vaccination for people who have had COVID-19 on the COVID-19 vaccination page.
After the 1st dose, the messenger RNA vaccine is 92% effective.
The 2nd dose is mainly used to provide long-term protection. The vaccine is thought to be 95% effective after two doses. For young people, disease-prevention efficacy is 100% after 2 doses.
See the Vaccine safety section on the COVID-19 vaccination page.
Symptoms after vaccination
Vaccination may cause symptoms such as redness at the injection site. Other problems may arise by chance and are unrelated to vaccination, such as a cold or gastroenteritis.
Most reactions are mild and short-lived. They may occur up to 8 days after vaccination. Reactions are less common in people over 55 years of age.
In a minority of people, the vaccine-induced reactions that prevent you from doing your daily activities for one or two days may occur. Reactions typically include fatigue, headache and muscle or joint pain. These reactions are less common in older adults. They are slightly more frequent after the 2nd dose.
The vaccines cannot cause COVID-19 because they do not contain the SARS-CoV-2 virus responsible for the disease. However, a person who has been in contact with the virus in the days prior to or following vaccination may still develop COVID-19. It is important to continue to follow the health instructions until most of the population has been vaccinated.
Known reactions to these vaccines
In most cases
(less than 10% of people)
* The majority of young people age 12–15 experience fatigue or a headache.
** This reaction can appear more than a week after the vaccination.
Fatigue, headache, and muscle and joint pain occur more often after the 2nd dose.
Approximately 2 in 100 000 people may have a serious allergic reaction after being given an RNA-based vaccine. This reaction is more common than is usually expected after a vaccine, but is still very rare.
What to do after vaccination
Recommendations to follow in the minutes after vaccination
Wait 15 minutes before you leave the place where you were given the vaccine. If an allergic reaction occurs, the symptoms will appear a few minutes after you get vaccinated.
If you have side effects, tell the person who gave you the vaccine immediately. They can treat you there.
Recommendations to follow at home
If you experience redness, pain or swelling at the injection site, apply a cold damp compress.
If necessary, take pain or fever medication.
When to consult
Consult a doctor if any of the following apply to you:
- You have serious or unusual symptoms.
- Your symptoms get worse instead of better.
- Your symptoms last more than 48 hours.
The start of vaccination does not mean the end of health measures. It will take several months to protect a sufficiently large proportion of the population. It is essential to continue to follow the health instructions until further notice.
Last update: June 17, 2021